Objective To investigate the bactericidal mechanism of electrolyzed oxidizing water (EOW) against Pseudomona aeruginosa (P.aeruginosa).Methods Bactericidal mechanism of EOW against P.aeruginosa was studied through intracellular protein leakage,nucleic acid,and cell membrane calcium ion permeability,2 ％ glutaraldehyde was used as positive control group,and normal saline (NS) was used as negative control group.Results The killing rates of EOW and 2％ glutaraldehyde to P.aeruginosa were both＞99.99％ with 30-second contact time,and 100.00％ with 60-second contact time.After 60-second contact with EOW,NS,and 2％ glutaraldehyde,the protein leakage of P.aeruginosa detected by bicinchoninic acid (BCA) were (96.00 ± 7.42),(94.15 ± 7.49),and (216.97 ± 10.35)μg/mL,respectively,difference was significant(F =613.20,P＜0.01),2％ glutaraldehyde group was higher than EOW group and NS group;protein leakage did not change with the increase of contact time(all P＞0.05).Electrophoretogram of random amplified polymorphic DNA showed high intensity dense band between 500-1000 Kb in EOW group and NS group,while 2％ glutaraldehyde group was without amplified bands.The fluorescence intensity of calcium ion of EOW group and 2％ glutaraldehyde group were both lower than that of NS group.Conclusion Bactericidal mechanism of EOW may be due to the damage of membrane permeability of P.aeruginosa,which causes Ca2+ leakage,but fails to cause protein leakage,the damage to nucleic acid is not obvious,DNA may not be a bactericidal target of EOW.